Hi @lgg96, how did you set the start and end position of the horizontal lines in the panel before applying them? If you set the start and end position to rhythmic grid position they will amalgamate and appear horizontally at the top, after condensing (as in your after screenshot), overriding so any manual positioning that you may have done before condensing.
If I set them to notehead, and changing the rhythm display (with Force duration) so that the beam and tie are not in the way (and so that is more clear that the gliss. is for the full duration of the notes, even if the third beat is not explicit), after condensing, I have two lines that I can individually position in Engrave mode:
Result:
Dorico file example:
horizontal lines condensing custom positioned.dorico (534.6 KB)